Method of oxidizing metals dissolved in mercury.



J. WHITING & G. F. BURGESS. METHOD or oxIDIzINS METALS DISSOLVED 1N MEDDURY. APPLICATION FILED DBO. 16, 1908. l 937, 1 28, Patented Oct. 19, 1909.

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JASPER WRITING, OF BOSTON, MASSACHUSETTS, AND CHARLES FREDERICK BURGESS, OF MADISON, WISCONSIN, ASSIGNORS TO THE` WHITING COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION 0F MAINE. I

METHOD OF OXIDIZING METALS DISSOLVED IN MERCURY.

Specification of Letters Patent.

Patented- Oct. 19, 1909.

Application led December 16, 1908. Serial No. 467,870.

To all whom it may concern:

Be it known that. we, (l) JASPER VHIT- ING and (2) C-IARLEs F. BURGEss, citizens of the United States, residing at (1) Boston, (2) Madison, in the `counties of (l) Suffolk, 2) Dane, and Statesof (l) Massachusetts, (2) Wisconsin, have invented certain new and useful Improvements in Methods of Oxidizing Metals Dissolved in Mercury, of which the following is a specification.

v This invention relates to the electrolysis of alkali metal salts vin cells employingV a cathode of mercury, the object of the invention being the provision of a method whereby the oxidation of an alkali metal existing as a component of an amalgam in contact with water or an oxidizing electrolyte may be accelerated. It is well known that such oxidation may be accelerated by local action, so-called, that is to say by providing in contact with the amalgam and anoxidizing electrolyte, a conductive body electronegative to thealkali metal. Thus it has been proposed to place upon the surface of the amalgam in the oxidizing compartment pieces or fragments of metals or their conductive compounds; ysuch substanceshowever are liable to reduction by the hydrogenevolved, or in 'use eventually become so coated or amalgamated with mercury as to destroy their elciency. The use .of .carbon or graphite 1n contact with the Iamalgam and water or oxidizing electrolyte hasnot heretofore proved satisfactory, .forthe reason that it is difficult to secure etlicient contact therewith, minute bubbles or lms of `hydrogen adhering to the surfaces and so preventing theperfectcon- 1 tact which ,is essential to satisfactory action.

It has also been proposedvto incorporatel iron with the carbon or toattach it thereto, but such expediente have been' commercially unsuccessful by the` reason lof the injurious effect of iron, exposed tothe act-ion ofthe amalgam, upon the mercury. f

We have'discovered: that under certain conditions it is practicabley to secure an excellent and enduring contact between v the amalgam and the carbon orfgraphite, where-5 by an eficient local action -may be secured and maintained. According to thev present invention this 1s etl'ected by establishing electrical contact between the carbon and the amalgam through a body, column or stratum of comparatively pure mercury or relatively dilute amalgam, usually underlying the l is a transverse vertical section lof the 0X1- dizing compartment of an electrolytic cell exhibiting certain embodiments of the invention; and Fig. 2 is avplan view of one form of carbon or graphite plate illustrated in Fig. 1.

The particular form of oxidizing compartment illustrated comprises a body portion 1 of cement, concrete or the like, which may be lined if desired with lass, slate, vitrilied earthenware or other suitable material as indicated in 2. The compartment is shown as subdivided by means of partitions 3, 3, into a series of ,wide shallow channels 4, 5, 6, disposed at successively lower levels and so arranged that the amalgam is directed through the several channels in succession, the denudedl metal returning from the lowermost channel to the decomposing compartment of the cell. Thisarrangement may be substantially as described in my copending application, Ser. No. 467,874 filed December 16, 1908. In the bottom of each channel is a carbon or graphite plate or slab 7, 8, 9, having integral projections or membersv 10 extending upwardly into contact with the water or loxidizing electrolyte 11. The amalgam flowing from the decomposing compartment through conduit 21 controlled by a mechanically actuated valve 22 onto the plate 9 in the uppermost channel G, lls thelower portions of thelongitudinal channels 12 between the projecting members lO'as indicated at 13 and flows therethrouglnthis flow being aided if desired by a suitable inclination of tho plate. The amalgam thenflowsin la similar manner over the plates 8 and 7, vthe .total path beneathV the liquid 11 being sufficient to completethe oxidation of the'contained alkali metal. the low'of the amalgam and equalize its distribution over the carbon plates, as well as to increase the active .carbon surface, We prefer Y to provide transverse channels 14 as In lorder to facilitate the sides and bottom of the channel I4, ni

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such'manner that the liquid nietal'lies in the form of a film or layer 15 beneath theplate 7 and in extended electrical contact therewith. This lm or layer 15 consists of comparatively pure mercury, the lighter amalgam being confined tothe upper surface of the plate: it is however in electrical contact with the amalgam through the metal in the lateral crevices 16, and is moreover in effective electrical contact with the carbon by reason of the pressure exerted by the overlying liquid. Inasmuch as the film or layer 15 consists of comparatively pure mercury,

is remote from theelectrolyte, is not subject to agitation or movement, andis under .a considerable hydrostatic pressure, it vmaintains a close and electricallyefficient .con-

tact with the carbon, and itspresence insuresa greatly increased rate of oxidation of the alkali metal. The same result may be accomplished by perforating the carbon plates at suitable intervals as illustrated at 17 in Figs. 1 and 2. The liquid metal fills the perforations as a quiescent column, the lower portion of which at least consists of substantially pure mercury. The contact in this case may be extended and rendered more effective by the presence of films or layers of mercury underlying the plate and filling such crevices as may normally exist between the plateand the cement body. A further means of accomplishing the same result is also illustrated 1n Fig. 1 in the form of a relatively deep well 18, shownas extending into a longitudinal rib 19 formed integral with the bottom of the carbon plate 9. Any

desired number of such wells may be provided, andl serve to improve the electrical contact by reason of the comparative purity ofthe mercury therein andthe pressure of the overlying liquid.

Inasmuch as comparatively pure mercury, as distinguished from an alkali metal amalgam, has little or no'action upon iron and certain other metals it isD practicable to still further increase the efiiciency of the contact by providing metallic connections extending from the carbon into contact with the comparatively pure mercury beneath the amalgam. For example, we have shown in Fig. 1 metallic screws 20 inserted in the lower face of the carbon plate 7 and exposed to the mercury in the layer or film 15. In this case the metal exhibits little or no tendency to pass into solution or to contaminate the mercury, and such solution or contamination as may occur' is localized and is without injurious effect upon the liquid metal as a whole. It will be obvious that similar means may be resorted to in order to increase the effectiveness of contact in any embodiment of the inv( ntion.

1. The method of oxidizing` metals dissolved'in mercury, which consists in providing carbon surfaces exposed to an oxidizing electrolyte and a moving body of amalgam, and establishingelectrical contact between the carbon and the amalgam through arelatively quiescent body ot' comparatively pure mercury. 2. The method of oxidizing metals dissolved in mercury, which consists in providing carbon surfaces exposed to an oxidizing electrolyte and a moving body of amalgam, and establishing electrical contact between the carbon and the amalgam through a relatively quiescent body of com aratively pure mercury underlying the aina gam.

3. The method of oxidizing alkali metals dissolved in mercury, which consists in providingcarbon surfaces exposed to an oxidizing electrolyte and a moving body of amalgam, and establishing electrical contact between the carbon and the amalgam by means of a metallic connection in contact with said carbon and a relatively quiescent body of comparatively pure mercury.

4. The method of oxidizing alkali metals dissolved in mercury, which consists in providing carbon surfaces exposed to'an oxidizl ving electrolyte and a moving body of amalgam, and establishing electrical contact between the carbon and the amalgam by means of a metallic connection in contact with said carbon and a relatively quiescent body of comparatively pure mercury underlying the amalgam.

In testimony whereof, we atiix our signatures in presence of witnesses.

CHARLES FREDERICK BURGESS.

- `lVit-nesses as to the signature of Jasper Whiting:

J oHN G. PALFREr, Bun'rria S, CHASE. Witnessesas to the signature Frederick Burgess:

J. M. WINTERBOTHAM,

S. T. WALKER.

of Charles 

